A process plant is typically a complex, multifaceted entity, such as a structured organization of physical elements operated for economic and other criteria that are often industry-specific. A process plant often has a number of different stakeholders who can affect its operation and/or who are affected by its operation. Critical to the operation of many process plants today is a process control system, which ensures that appropriate parameters are measured and actions taken, plant personnel are kept informed, abnormal situations are identified and addressed, and business processes are integrated. Automation and control systems are employed in diverse applications, such as refining and petrochemical plants, petroleum and natural gas supply chains, pulp and paper manufacturing, electrical power generation, chemical production, food production, wastewater treatment, discrete product manufacturing, cable-laying ships, tunnel ventilation control, and mining operations.
A process control system typically includes a process controller in communication with field devices such as process sensors, process actuators, and user interfaces. The process controller may receive measured values of process variables from the process sensors and may control positions of process actuators to maintain the process variables within desired ranges. Various communication protocols between a process controller and its nodes have been developed. As new communication protocols are developed, process controllers may be upgraded to support these new communication protocols.
Field devices utilizing new communication protocols, however, may be “backwards compatible.” That is, a process controller that has not been upgraded may be able to communicate with such a field device at some minimal level, without being able to utilize the full functionality of the field device.
Field devices utilizing new communication protocols may be added to existing process control systems without upgrading a process controller for several reasons. Upgrading a process controller or associated circuitry to support a new communication protocol may require shutting down operation of all or a significant part of a process plant while upgrades are made. Upgrading the process controller or associated circuitry may also be considered too expensive.